Hammer with sustained blow



March 9, 1965 L. GIANELLI HAMMER WITH SUSTAINED BLOW Filed April 19, 1962 INVENTOR. Lac/EN GIANELLI jlndrus (f Star/{e A TTORNEYS United States Patent 3,172.,e3s HAMMER WITH SUSTAH'JED BLOW Lucien Gianelli, Onex, Geneva, Switzerland, assignor to Andre .l. Pint, Thalwil, Zurich, Switzerland Filed Apr. 19, 1962, Ser. No. 188,728 3 Claims. (Cl. 145-29) This invention relates to a hammer with a sustained blow and which does not have a rebound.

The invention has been applied to manual hand hammers and will be so illustrated here, although certain principles of the invention are applicable to power hammers and the like.

In carrying out the invention the hammer is provided with a primary striking mass and a separate secondary relatively floating mass of greater weight which is carried by the primary mass with a hydraulic cushion therebetween whereby the secondary mass provides a sustained blow by reason of a time lag in its striking movement and effectively holds the primary mass against rebound.

The hydraulic cushion is constructed to permit a given displacement of the fluid by the secondary mass as it continues to move after the primary mass is stopped by striking an object, and means such as a spring returns the secondary mass to normal relation with the primary mass, thus providing for a return of the hydraulic fluid previously displaced by movement of the secondary mass.

Other objects and advantages will appear in the course of the following description.

The drawings illustrate the best mode present contemplated of carrying out the invention.

In the drawings:

FIG. 1 is a perspective view of a hand hammer embodying the invention;

FIG. 2 is a central longitudinal section through the hammer; and

FIG. 3 is a transverse section of the hammer head taken on line 33 of FIG. 2.

The hammer illustrated comprises a body 1 having a handle 2 secured thereto centrally of one side and extending at right angles therefrom.

The body 1 is a hollow shell and may be of any suitable shape, that shown being cylindrical, with two opposite ends 3 and 4 welded in place to provide a sealed chamber 5 of substantial size therein. End 3 has a central opening therethrough which is normally closed by the screw plug 6.

The outer wall of body 1 extends beyond the ends 3 and 4 and receives the opposite end heads 7 and 8 which may be press fit therein or otherwise secured, and which constitute the striking members of the hammer. End head 7 has a recess 9 in its inner surface to accommodate the head of the screw plug 6.

The body 1, together with the end heads 7 and 8, comprise the primary striking mass of the hammer, and either end head may be used to strike the hammer blow.

The secondary mass is a piston-like block it of greater weight than the primary mass and disposed within chamber 5 with its ends generally spaced from the corresponding ends 3 and 4 of body 1. The space in the chamber 5 surrounding block 10 is substantially filled with a hydraulic liquid 11, preferably leaving a small air space 12 for cushion purposes.

A suitable passage is provided between the opposite ends of chamber 5, that shown being an axial hole 13 through the block 10 and of a size that will restrict the free flow of liquid 11 from one end of the chamber to the other end as when mass 10 continues to move toward the striking end of the hammer after the corresponding head 7 or 8 has struck its hammer blow.

For the purpose of returning the mass 10 to a central 3,l72,438 Patented Mar. h, 1965 normal position, as shown, a spring 14 is disposed between each end of the mass and the corresponding end 3 or 4.

In operation, when the primary mass strikes its blow, the inertia of the secondary mass causes it to continue to move in the same direction and to transmit a sustained force through liquid 11 to the corresponding end of body 1 and head '7 or 8, and thence to the object which has been struck. This sustained force holds the primary mass from rebounding and maintains the striking pressure upon the object. At the same time, the mass it displaces some of the liquid 11 from the striking end and the liquid flows through hole 13 to the opposite end of chamber 5.

The size of hole 13,- is such as to provide the necessary displacement of liquid over the time desired for maintaining the striking pressure. Because of this sustained blow by the secondary mass 10 the primary mass is prevented from rebounding or bouncing back after striking its blow.

Various modes of carrying out the invention are conplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention.

I claim:

1. A hammer comprising a primary mass having a head and a hollow sealed chamber thereon and disposed to move in a direction to strike a blow with the head, a secondary mass of greater weight and carried by said primary mass within said chamber directly behind said head and spaced from the latter, said secondary mass being adapted to move longitudinally thereof in the direction of the hammer blow, energy transmitting liquid means disposed in said chamber between said secondary mass and said head, and means restricting the displacement of the liquid by said secondary mass to thereby apply a striking blow from said secondary mass simultaneously with and as a part of the striking blow of said primary mass and transmit a continuing hammer blow from said secondary mass through said liquid and head after the latter has delivered said striking blow.

2. The construction of claim 1 in which said restriction means comprises a passage by-passing said secondary mass and providing for the restricted flow of liquid from between the secondary rnass and head at one end of said chamber to the opposite end thereof, and spring means between said secondary mass and said head to return said secondary mass to its original position following dissipation of the energy thereof.

3. A hammer having a primary mass which comprises a hollow cylindrical body having closed ends to form a sealed chamber therein and having striking heads at its opposite ends, a secondary mass comprising a piston-like body of greater weight than said primary mass and disposed within said chamber with its ends spaced from the corresponding ends of the chamber to provide for axial movement of the secondary mass within said chamber, energy absorbing means comprising liquid substantially filling said chamber, a restricted passage for flow of liquid from one end of said chamber to the other, and spring means between each end of said secondary mass and the corresponding end of said chamber to return said second ary mass to a substantially central position in said chamber following displacement thereof by a hammer blow.

References Cited in the file of this patent UNITED STATES PATENTS 2,592,013 Curley Apr. 8, 1952 FOREIGN PATENTS 59,996 Norway Oct. 24, 1938 1,163,525 France Apr. 28, 1958 

1. A HAMMER COMPRISING A PRIMARY MASS HAVING A HEAD AND A HOLLOW SEALED CHAMBER THEREON AND DISPOSED TO MOVE IN A DIRECTION TO STRIKE A BLOW WITH THE HEAD, A SECONDARY MASS OF GREATER WEIGHT AND CARRIED BY SAID PRIMARY MASS WITHIN SAID CHAMBER DIRECTLY BEHIND SAID HEAD AND SPACED FROM THE LATTER, SAID SECONDARY MASS BEING ADAPTED TO MOVE LONGITUDINALLY THEREOF IN THE DIRECTION OF THE HAMMER BLOW, ENERGY TRANSMITTING LIQUID MEANS DISPOSED IN SAID CHAMBER BETWEEN SAID SECONDARY MASS AND SAID HEAD, AND MEANS RESTRICTING THE DISPLACEMENT OF THE LIQUID BY SAID SECONDARY MASS TO THEREBY APPLY A STRIKING BLOW FROM SAID SECONDARY MASS SIMULTANEOUSLY WITH AND AS A PART OF THE STRIKING BLOW OF SAID PRIMARY MASS AND TRANSMIT A CONTINUING HAMMER BLOW FROM SAID SECONDARY MASS THROUGH SAID LIQUID AND HEAD AFTER THE LATTER HAS DELIVERED SAID STRIKING BLOW. 